The prior art proposes numerous devices that offer means for remotely executing operations such as cutting, trimming and/or pruning trees. These devices typically comprise at least a tree cutting means, such as a power chain saw, round saw or band saw mechanism attached to the outer end of a mobile boom mounted on a self-powered vehicle, or the like. Other prior art devices further comprise a tree holding means for grasping the portion of the branch or trunk of a tree destined to be cut and, once it is cut, for manipulating the latter up to a desired location nearby.
While these prior art devices can generally fulfill the main objective of enabling an operator standing at a safe distance from the operation to remotely cut, trim and/or prune a tree, they also offer disadvantages that will be described hereinafter using typical prior art examples.
U.S. Pat. No. 4,063,359, to A. J. Luscombe (1977), proposes a vehicle mounted boom apparatus having a chain saw mechanism mounted thereon and being mounted for shifting movement about a plurality of axes relative to the boom apparatus. Although this device may allow appreciable dexterity in reaching and cutting a branch on a standing tree, it does not offer a clamping means for stably holding the branch while it is being cut, or for manipulating the latter once it is cut away from the tree.
U.S. Pat. No. 4,281,693, to D. C. Moulson (1981), proposes a typical hydraulic feller head attachment which offers a cutting means coupled to a tree clamping means, here represented by a pair of gripping arms encased in a substantially U-shaped housing. While being effective at stably holding the branch or trunk of a tree during the cutting and subsequent handling operations, the cut is invariably at a right angle relative to the longitudinal axis of the branch or trunk, as well as immediately adjacent the gripping arms. These last two characteristics are not necessarily practical in specific trimming and pruning operations on a tree since there are some occasions where the cut must be made at a particular angle and distance relative to the gripping arms assembly. It is to be noted that this type of feller head is often encountered in the tree harvesting industry, and usually comprises additional feeder and delimbing means directly coupled to the head attachment.
U.S. Pat. No. 3,389,728, to A. J. Calis (1968), proposes a tree cutting means and a tree holding means attached to the outer ends of two individually operated carrier booms. Although this approach potentially overcomes the disadvantages of the two prior art devices described above, one skilled in the art readily realizes the difficulty raised by the delicate task of operating the two articulated booms individually or simultaneously. The task gets delicate even more so when the cutting means has to cut an horizontal branch on the opposite side of the holding means, in a crisscrossed configuration with the latter.
Furthermore, a common disadvantage of the prior art is a head attachment which do not offers much in terms of error margins to the operator when the latter has to precisely align a slightly wobbling head attachment against a branch, particularly when the articulated carrier boom is stretched to its full extent to reach high in a tree.
Against this background, there exist a need for a new and improved tree pruning and trimming head that avoids the aforementioned disadvantages.
It is a general object of the present invention to provide such a tree pruning and trimming head.